I have been to Thailand a few times and it’s fantastic every time.
First, I recommend the street food in Bangkok. The best Pad Thai noodles I’ve ever had was made off a little wagon for a dollar or two.
And, make sure you order a Thai iced tea and coffee, they are a lot sweeter than I’m used to because they use condensed milk with sugar but are so tasty. I also loved scuba diving off the island Koh Tao.
I got my PADI scuba divers license there and it was super cheap and breathtakingly beautiful. If you have a little extra time check out some Buddhist temples, watching the rituals and people burning candles and incense was so inspiring, I’ll never forget it.